SPG or Not? (Dive computer w/ air int)

[wordizbon]

Hello. I'm still a new diver but I've upgraded my regulator, 1st and 2nd. I did not get a SPG with it and I'm wondering, do I get one or just go with a dive computer with air integration. The gauge I saw from the same manufactor is 20% of the cost of the computer.

I do own a Shearwater Peregrine I purchased a couple of months before they decided to drop the air integrated one. Eventually I do plan on upgrading this computer I have but I just thought, due to the SPG being less prone to "fault", it would still serve as a backup when I eventually do upgrade the computer.

Thoughts? Thanks in advance.


Dee

 

[Doctorfish]

I like to have an SPG backup. If the AI doesn't link or craps out, your dive is over.

 

[rongoodman]

If you already have a Peregrine without AI just add a plain SPG. AI is nice to have but not a necessity.

 

[Divin'Papaw]

Hello. I'm still a new diver but I've upgraded my regulator, 1st and 2nd. I did not get a SPG with it and I'm wondering, do I get one or just go with a dive computer with air integration. The gauge I saw from the same manufactor is 20% of the cost of the computer.

I do own a Shearwater Peregrine I purchased a couple of months before they decided to drop the air integrated one. Eventually I do plan on upgrading this computer I have but I just thought, due to the SPG being less prone to "fault", it would still serve as a backup when I eventually do upgrade the computer.

Thoughts? Thanks in advance.


Dee

Great question. You will find many other threads via search that already cover this topic. You will find that some people prefer an SPG with a non-AI computer, others prefer an AI computer with an SPG backup, or some go with just AI with no SPG backup. It is a personal decision that you must make for yourself once you've weighed the pros and cons of those 3 primary options.

 

[inquis]

It's a preference, really. Shearwater transmitters are quite reliable, and SPGs can fail with misleading info (e.g., stuck on 1500 psi). I prefer AI, but I do keep a battery in the dive kit. I also have an SPG in the kit as a 2nd backup (or loaner). What I will not do is run both, much as I never ran 2 SPGs before AI.

Certainly, the easiest path is a simple brass & glass SPG from DGX for $90 for now.

 

[DutchDiverDude]

There are conflicting opinions on this.
More things = more failure points = bad.
SPG + Transmitter on the same tank doesn't add much. Both can fail, having 2 has zero added value until one fails which is more likely to happen if you have 2. Regardless, the dive is over.
Having doubles and SPG/AI on both adds something, since you can monitor 2 (manifolded tanks), but added value is minor:
In case isolation is necessary, you can still check both tanks, that's a plus, but the dive is over anyway.
An SPG is easier to quickly check pressure before a dive, since no electronics needs to start up, another minor plus.

So a bit more convenience + more information in one case of failure, versus higher likelihood of another failure.
This combined with a the SPG being a piece of non-critical equipment causes the conflicting opinions.
According to 'plan your dive, dive your plan' + experience, you should know exactly how long you can dive before you are low on gas. The SPG is only extra confirmation, and a bubble check should already confirm that no gas is leaking. I am confident that I can do most of my dives without an SPG, as long as I can check the tank pressure right before the dive, because I know how long I can dive at what depth with one tank or set of doubles.

Still, I carry 2 AI computers, one set to gauge mode. The main reason for that is that I first was using a Suunto Cobra which is AI through a HP hose, which I later replaced with a Perdix AI. I was considering, as you are now, to use a backup SPG. I was also considering using a backup computer since I do technical/deco diving. The Cobra was perfect for this, since one tool covers both. The perdix is my main, the Cobra tags along. I usually use the cobra to check the pressure before a dive, and after about 150 minutes I usually compare both tank pressures once just to confirm that they are similar. But mostly it is there only for backup SPG AND backup computer. That way I have extra redundancy without extra risk or bulk.

For 'holiday' diving in warm water with a single tank, I would probably bring take the AI computer and just pack a hose and SPG. If it fails, you can estimate how long you can still dive and end the dive at the safe margin thereof (assuming no gas leaks). If it is for whatever reason not repairable, swap with the SPG and do the rest of your diving like that.

 

[arew+4]

A hose connected air integrated computer no sense in back up gauge, any failure of computer is an abort event.

Wireless air integration I would keep a spg, in the event the transmitter failed you would not need to abort

 

[lexvil]

Moot point, you don’t have an air integrated computer so you either get an SPG or change to an AI computer. I use AI and do not carry an SPG except in the save a dive kit, only used it once in the past 15 years when I forgot to pack my computer.

 

[tursiops]

due to the SPG being less prone to "fault"

Arguable.
Get the SPG, but get a cheaper one than the one you are looking t. use it now. When you get an AI system, put the SPG in your gear bag as a spare if needed. Highly likely you will never need it.

 

[KenE]

I faced this dilemma when I added the AI. The SPG did save my dive on a couple occasions when the AI dropped off. So, instead of removing the SPG, I put it on a shorter hose and routed it over the left shoulder and connected it to the corrugated inflator hose. This eliminated the hose around the left side and put it where I can see it if I ever needed. I have since upgraded to a SW Perdix 2 and have not had any AI issues. Still considering removing the SPG from the rig, but don't see any reason. I thought about removing it when travelling but then realized that would be the most inconvenient dive to abort due to AI, so I left it on. It takes about 2 seconds to route it and connect to the hose, so other than the "added failure point" it has no negative impact. Several years later, it is still there, never failed, no issue, however, AI has not failed either.

So, it is a personal choice!